1. Field of the Invention
The present invention relates generally to typical curb valve boxes having an upper opening for receiving a valve box cover and in particular with a valve box adapter usable with the curb valve box to elevate the cover to a new pavement level.
2. Description of the Prior Art
A common requirement in street paving is an extender or adapter for typical curb valve boxes protecting and securing cutoffs and meters below street level. In many cases, a metal extender ring of the necessary thickness is welded to the top of the valve box to raise the level of the cover as required. Other techniques include utilization of screw-threaded extender rings. These techniques are generally effective to accomplish the desired result but in many instances are expensive or require considerable installation labor. Moreover, such rings sometimes break under heavy traffic or otherwise become loose as a result of vibration. See, for example, U.S. Pat. Nos. 4,325,405; 3,408,778; and 3,533,199.
While these improvements are in common use, it is oftentimes necessary to raise the level of the manhole cover even more by utilizing shims beneath the ground ring. This technique requires removal of the soil around the ring to permit installation of the shims and its replacement thereafter. Again, this procedure is involved and labor intensive.
Thus there is a need for a relatively inexpensive and more reliable way of elevating valve box covers to preselected pavement levels that permits expeditious installation and provides a relatively vibrationless unit.